Abstract
Downhole scale deposition poses significant challenges for artificial lift wells, as it leads to increased power demand on the drive motor and premature equipment failure. Chemical treatments often struggle to effectively target the scale deposition, making it crucial to find a more efficient technique to improve well run life and reduce operational expenditures. This paper presents a case history of two progressive cavity pump (PCP) wells in Oman that underwent a trial of electromagnetic treatment to enhance scale protection.
Historically, these two wells had an average run-life of 8 and 9 months, respectively, with frequent calcite scale issues resulting in equipment failures and production downtime. The operator conducted a trial of electromagnetic technology to evaluate its effectiveness as an alternative solution for improved performance. Key performance indicators (KPIs) were established to measure comparative run-time, production rates, and flow assurance.
Pre-installation performance assurance was achieved through analysis of well conditions and architecture, electromagnetic field (EMF) simulation modeling, scaling predictions, and onsite testing. After installation, the pulsed electromagnetic signals facilitated the accelerated formation of scale crystals in fluid nanosuspension and modified their morphology to prevent adhesion to surfaces.
During the trial period, both wells exhibited improved and stabilized KPIs, including gross volume, net oil, motor frequency, and basic sediment and water (BS&W). Most notably, the gross volume production and motor frequency remained constant. In well 1, the run-time increased from 8 months to 21 months, and in well 2, it increased from 9 months to 16 months until the trial concluded. In well 2, the trial ended due to a non-scale related integrity issue that required intervention. During the intervention, the pump and rods were inspected and reported to be scale-free and in good condition. With run life improvements of over 250% and 80% in the respective trials, along with enhanced KPIs, the trials were considered successful.
In addition to the operational benefits, this technology offers additional advantages in terms of cost efficiency, reduced HSE risk, and a lower carbon footprint for wellsite operations. It eliminates or reduces the need for ongoing chemical injection, interval acid washes, mechanical scale removal, and replacement of downhole equipment. Over time, the economics of this treatment option further improve.
Scale deposition is a challenge for all types of wells, but it particularly affects mature artificial lift wells with higher water cut. Given their marginal economics and the associated costs of intervention and equipment replacement, finding effective remediation options can be challenging. These wells provide an ideal environment for scaling, but the flow dynamics of chemical treatments often struggle to access and treat the small apertures of PCPs and ESPs. Operators have been seeking a more efficient solution for some time to address these issues.
